Red beets have long been a common source of various nutrients, and particularly of sugar and betaine. Further useful compounds obtained from red beet include betalains which represent a chemically diverse group of red to violet colored betacyanins (e.g., amaranthin, isoamaranthin, etc.) and typically yellow-colored betaxanthins (e.g., vulgaxanthin), which have found use as pharmaceutical and food coloring agents and as antioxidants.
Numerous manners of producing betalain preparations are known, and commonly start from comminuted beet root or root peelings. Other known source materials include root cell suspension culture, cactus pear, and selected higher fungi. Where betalains are prepared from beet juice or root macerates, preparations will typically have a betalain content of equal or less than 1 wt % and generally include significant quantities of sugars and other components. For example, WO 98/26792 describes various methods of preparing betalain extracts from root pulp that is further processed using crosslinked dextran chromatography. Alternatively, lyophilized beet can be used as starting material as described in US 2003/0036565, which is subsequently ground, solvent extracted, and subjected to crosslinked dextran chromatography to yield distinct betalain fractions. Typical known process employing spray drying of a beet juice concentrate will yield a powder comprising about 0.4 wt % betalains. Consequently, while most of these processes are conceptually simple, the concentration of betalains is generally below 1 wt %. Moreover, substantial quantities of non-betalain material are present and require further purification or other processing for removal.
In still other known methods (e.g., U.S. Pat. No. 4,238,518 or GB patent 1 559 275), stabilized betanidine extracts are prepared using ion exchange chromatography in which, among other compounds, betaxanthins are removed to yield a concentrated pigment preparation that is then dehydrated, re-dissolved, and combined with a stabilizing agent to form a thermally stable pigment powder. Such method advantageously allows for production of a relatively concentrated dry form of beet pigments, however, removes significant portions of the betaxanthins and certain betacyanins. Similarly, Garin et al. describe in U.S. Pat. No. 4,409,254 a process in which beet root extract is subjected at very low pH to chromatography using a non-ionic resin to so produce a concentrated eluate that is concentrated in betanin and other adsorbed solids. Such concentrated liquids may comprise 4.5 wt % betanin and can be dried to a betanin content of about 25 wt %. Unfortunately, such preparations are generally hygroscopic, readily clump, and tend to deteriorate relatively quickly.
In an effort to reduce sugar content of a betalain preparation, von Elbe et al. describe in U.S. Pat. No. 4,027,042 a process in which beet juice or beet pulp is subjected to a yeast fermentation to reduce sucrose concentration. While such process yields a concentrated pigment preparation and successfully eliminates sucrose, other fermentation byproducts are introduced, which are chemically unidentified and account for 25 wt % (or even more) of the final product.
Unfortunately, compounding and storage of currently known betalain preparations are negatively affected by the non-betalain components. For example, betalains prepared from freeze-dried beet juice are often clumpy and highly hygroscopic. Therefore, such preparations are notoriously difficult to weigh out and aliquot, especially where relatively small quantities are distributed. Worse yet, most of the currently known dry betalain preparations are limited to betalain concentrations of about 1 wt % (total betalains), and almost all of the attempts to increase the betalain concentration by extraction or other means also leads to an increase of hygroscopicity and clumping. In still other known preparations, and particularly in those with relatively high betalain content, non-betalain components will typically lead to substantial loss of stability in the absence of a stabilizing agent. Moreover, and often irrespective of the betalain content, non-betalain components are typically associated with resistance of the betalains to completely dissolve in aqueous media.
Therefore, while numerous compositions and methods of solid betalain preparations are known in the art, all or almost all of them suffer from disadvantages. Consequently, there is still a need to provide improved compositions and methods for solid betalain preparations.